Radio access networks enable wireless transmissions of information to and from user equipment. Each transmission is carried out with a variety of service attributes of values that have to be determined for the transmission. The term radio access network is used in this document to denote a complete network that can be accessed by radio connections, e.g. a whole cellular network, the core network parts inclusive.
In future radio access networks, sophisticated service control mechanisms, like the control of the Quality of Service (QoS) provided for each transmission, can play an important role. Such service control mechanism can be used for differentiating between different applications, like real-time versus non-real-time applications, or between different user groups, e.g. business versus low-budget users. In 3G (3rd generation) networks, the provision of a certain QoS and a QoS-based billing is an inherent part of the service models. Service control mechanisms are realized by varying the values of attributes used for a transmission.
A customer can register user equipment for a specific radio access network In order to enable service control mechanisms, in addition a subscriber specific service profile has to be agreed upon. Such a service profile defines e.g. the quality of service that is allowed or guaranteed for transmissions between the user equipment and the network, and depends usually on what the customer is willing to pay for these transmissions. More specifically, the subscribed service profile contains or refers to values of different service attributes that characterize the quality of a transmission. The values defined by the subscribed service profile can be used for all transmissions to and from the respective user equipment. Alternatively, the user equipment is allowed to request for each transmission values for the required service attributes that are below or equal to the level of the subscribed values of attributes. For the case that a transmission is requested without explicit indication of desired values for the required service attributes, default attributes have to be provided.
There is a considerable number of service attributes that may have to be determined for each connection. For UMTS (Universal Mobile Telecommunications System), QoS attributes have been specified in 3GPP TS 23.107 V3.4.0 (2000-07); “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; QoS Concept and Architecture; Release 1999”. All transmissions are distributed to four different classes of traffic, a conversational class, a streaming class, an interactive class and a background class. The main distinguishing factor between these classes is how delay sensitive the traffic is. The conversational class is meant for traffic which is very delay sensitive while the background class is the most delay insensitive traffic class. Conversational class and streaming class are mainly intended to be used to carry real-time traffic flows. An example for conversational class traffic is voice and an example for streaming class traffic is streaming video. Interactive class and background class are mainly intended to be used to carry non-real-time traffic flows. An example for interactive class traffic is web browsing and an example for background class traffic is background download of emails. The standard defines which attributes have to be defined for which class and also gives value ranges for the different service attributes.
According to the standard, for each of the four classes the maximum bitrate, the delivery order, the maximum SDU (Service Data Unit) size, the SDU error ratio, the residual BER (Bit Error Ratio), the delivery of erroneous SDUs, and the allocation/retention priority have to be fixed. An indication of the traffic class itself also forms one of the attributes required for all classes. For the conversational class and the streaming class an SDU format information, a transfer delay and a guaranteed bitrate have to be determined in addition. For the interactive class a traffic handling priority (THP) has to be determined in addition.
All subscribed attributes are currently stored together with other information in the HLR/HSS (Home Location Register/Home Subscriber Server) of the user equipment in the radio access network,with which the user equipment is registered. The mentioned UMTS standard does not clearly define, however, how the QoS attributes stored in the HLR/HSS are to be taken in to account when deciding the attribute set that is to be used for a specific connection. The standard only specifies that one QoS profile is stored for each customer subscription. The user equipment can then request specific values of service attributes, the subscribed profile defining the upper limits for the provided service. To be able to use services with a high transmission quality, a user has therefore to subscribe a QoS profile with values of service attributes that enable a high quality.
The standard proposes to use the subscribed profile as well as default QoS profile. The disadvantage of such an approach is that even if a customer does not require any specific values of attributes for some traffic stream, a possibly high subscribed QoS profile is used without need.
Another problem arises from an approach proposed in UMTS standard, 3G TS 23.060, version 3.4.0. According to this standard it is possible for user equipment to leave some of the QoS attributes undefined in a PDP (Packet Data Protocol) context activations However, the standard does not define any functionality that would enable a network to intelligently evaluate the user-defined QoS attributes when determining the rest of the attributes. The missing attributes are simply fetched from HLR/HSS. This may lead to a situation where there is a conflict between the requested and the fetched QoS attributes. Such a conflict is given for example, if a very low delay is requested by the user equipment, which is essential for real-time traffic, and a very good subscribed packet error rate, which would only be essential for non-real-time traffic, is fetched from the HLR/HSS. Such a combination of attributes is impossible to implement.
Further problems in assigning values of service attributes to requested transmissions arise from the fact that a user of a user equipment is not necessarily confined to requesting a connection in the radio access network in which the equipment is registered. In particular in local wireless hotspots, like in hotels and airports, a locally restricted radio access network may be provided for connections to the public internet or to a corporate network Such a wireless access network can be realized for example as wireless local area network (WLAN). A user equipment can access the local radio access network, if it is owned equally by the operator of the radio access network with which the user equipment is registered, or if it is owned by another operator having a roaming agreement with the operator of said radio access network with which the user equipment is registered.
Each user equipment is equipped with a smart card, such as a GSM (Global System for Mobile communication) Subscriber Identification Module (SIM), which contains information needed for user authentication and billing in a public radio access network, in particular a cellular network, in which the respective user equipment is registered. The operator of the public radio access network, e.g. a GSM or 3G network, may offer broadband wireless services additionally in a local radio access network, e.g. a WLAN, for the cellular users by utilizing the existing cellular infrastructure for user authentication and billing. The authentication and billing information is carried between the local radio access network and the public radio access network through gateways. Proprietary protocols take care of the signaling between the different network elements.
In conventional WLANs, all users receive a similar service from the network, the so called “best-effort service”. This service simply provides means to the user equipment to send traffic to and receive traffic from the network. This approach, however, does not allow to provide different levels of service or qualities of service to different subscribers